The present invention relates to an offshore structure for supporting a production platform above the water for subsea walls, particularly for shallow wells which can be drilled by jackup rig.
U.S. Pat. No. 4,087,983 discloses an offshore platform which extends from the subsea location and includes a plurality of knuckle joints which are arranged circumferentially and includes a very large base footprint and has braces extending from the outer portions of the base to the central tubular member.
U.S. Pat. No. 3,572,044 discloses an offshore platform which is lowered from a floating rig and after the base is set which includes angular piling under the corner leg guides of the base and around the exterior of the wellhead unit. This structure has a very large footprint and is used only for setting the wellhead unit and then recovered.
U.S. Pat. No. 3,482,408 discloses a telescoping caisson which connects from a subsea location to a production deck above the surface of the water and is held in location by a series of guy wires.
U.S. Pat. No. 4,222,682 discloses a sea bottom structure for supporting a platform above the water surface and includes a large base including floatation tanks to support the column connecting between the platform and the base during transportation.
U.S. Pat. No. 4,558,973 discloses a structure for clamping about a subsea well conductor pipe to support it is an erect position and such structure includes a wide spread base with half shells secured to the base, extending upwardly, is clamped around the conductor pipe and angular supports extending angularly from the corners of the base to the half shells near their upper ends to support them in their erect position.